Even though I have not talked to Fencer, I can almost say I'm 99% sure if you play someone in the same household will not be a problem unless you are purposely trying to cheat the rating system. (So if you start playing 2-3 games with someone in the same household a day, then it might start being a problem.) And if that is the case, I would then recommend you always play unrated games with each other. Again, just my thoughts.